Migrate AboutActivity to viewpager2

app/src/main/java/org/schabi/newpipe/about/AboutActivity.java

@@ -8,16 +8,18 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
-import androidx.fragment.app.FragmentPagerAdapter;
-import androidx.fragment.app.FragmentStatePagerAdapter;
-import androidx.viewpager.widget.PagerAdapter;
-import androidx.viewpager.widget.ViewPager;
+import androidx.lifecycle.Lifecycle;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.viewpager2.adapter.FragmentStateAdapter;
+import androidx.viewpager2.widget.ViewPager2;
 
 import com.google.android.material.tabs.TabLayout;
+import com.google.android.material.tabs.TabLayoutMediator;
 
 import org.schabi.newpipe.BuildConfig;
 import org.schabi.newpipe.R;
@@ -64,20 +66,20 @@ public class AboutActivity extends AppCompatActivity {
                     "https://github.com/lisawray/groupie", StandardLicenses.MIT)
     };
 
+    private static final int POS_ABOUT = 0;
+    private static final int POS_LICENSE = 1;
+    private static final int TOTAL_COUNT = 2;
     /**
-     * The {@link PagerAdapter} that will provide
+     * The {@link RecyclerView.Adapter} that will provide
      * fragments for each of the sections. We use a
-     * {@link FragmentPagerAdapter} derivative, which will keep every
-     * loaded fragment in memory. If this becomes too memory intensive, it
-     * may be best to switch to a
-     * {@link FragmentStatePagerAdapter}.
+     * {@link FragmentStateAdapter} derivative, which will keep every
+     * loaded fragment in memory.
      */
     private SectionsPagerAdapter mSectionsPagerAdapter;
-
     /**
-     * The {@link ViewPager} that will host the section contents.
+     * The {@link ViewPager2} that will host the section contents.
      */
-    private ViewPager mViewPager;
+    private ViewPager2 mViewPager;
 
     @Override
     protected void onCreate(final Bundle savedInstanceState) {
@@ -93,14 +95,25 @@ public class AboutActivity extends AppCompatActivity {
         getSupportActionBar().setDisplayHomeAsUpEnabled(true);
         // Create the adapter that will return a fragment for each of the three
         // primary sections of the activity.
-        mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
+        mSectionsPagerAdapter =
+                new SectionsPagerAdapter(getSupportFragmentManager(), getLifecycle());
 
         // Set up the ViewPager with the sections adapter.
         mViewPager = findViewById(R.id.container);
         mViewPager.setAdapter(mSectionsPagerAdapter);
 
         final TabLayout tabLayout = findViewById(R.id.tabs);
-        tabLayout.setupWithViewPager(mViewPager);
+        new TabLayoutMediator(tabLayout, mViewPager, (tab, position) -> {
+            switch (position) {
+                default:
+                case POS_ABOUT:
+                    tab.setText(R.string.tab_about);
+                    break;
+                case POS_LICENSE:
+                    tab.setText(R.string.tab_licenses);
+                    break;
+            }
+        }).attach();
     }
 
     @Override
@@ -162,40 +175,30 @@ public class AboutActivity extends AppCompatActivity {
     }
 
     /**
-     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
+     * A {@link FragmentStateAdapter} that returns a fragment corresponding to
      * one of the sections/tabs/pages.
      */
-    public class SectionsPagerAdapter extends FragmentPagerAdapter {
-        public SectionsPagerAdapter(final FragmentManager fm) {
-            super(fm, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
+    public static class SectionsPagerAdapter extends FragmentStateAdapter {
+        public SectionsPagerAdapter(final FragmentManager fm, final Lifecycle lifecycle) {
+            super(fm, lifecycle);
         }
 
+        @NonNull
         @Override
-        public Fragment getItem(final int position) {
+        public Fragment createFragment(final int position) {
             switch (position) {
-                case 0:
+                default:
+                case POS_ABOUT:
                     return AboutFragment.newInstance();
-                case 1:
+                case POS_LICENSE:
                     return LicenseFragment.newInstance(SOFTWARE_COMPONENTS);
             }
-            return null;
         }
 
         @Override
-        public int getCount() {
+        public int getItemCount() {
             // Show 2 total pages.
-            return 2;
-        }
-
-        @Override
-        public CharSequence getPageTitle(final int position) {
-            switch (position) {
-                case 0:
-                    return getString(R.string.tab_about);
-                case 1:
-                    return getString(R.string.tab_licenses);
-            }
-            return null;
+            return TOTAL_COUNT;
         }
     }
 }

app/src/main/res/layout/activity_about.xml

@@ -30,7 +30,7 @@
 
     </com.google.android.material.appbar.AppBarLayout>
 
-    <androidx.viewpager.widget.ViewPager
+    <androidx.viewpager2.widget.ViewPager2
         android:id="@+id/container"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"